The invention relates to a control unit for a motor vehicle and in particular to a control unit for a transmission in a motor vehicle and to a control unit for an air induction system in a motor vehicle.
Automatic transmissions and engines for passenger cars are generally electronically controlled by an electronic control system. The electronic control system receives and evaluates, among others, the signals from one or more sensors in the motor vehicle. A sensor of this kind is used, for example, to measure the pressure in the hydraulic fluid of the transmission or the vacuum in the intake section of the engine.
German Utility Model No. DE 295 13 950 U1 discloses a control unit for a motor-vehicle transmission. The transmission has an electronic control circuit connected electrically to at least one pressure sensor for measuring the hydraulic pressure in the transmission, the pressure sensor and the electronic control circuit are accommodated in a common housing.
Control units mounted on or in an assemblyxe2x80x94the engine or the transmission of a motor vehicle for examplexe2x80x94must be configured with particular care with regard to the dissipation of heat given off by electronic components during operation because of the high ambient temperature. There are many different embodiments of pressure-measuring sensors, e.g. in the form of ceramic pressure cells, metal diaphragms with piezoresistive resistors and various silicon sensors. Common to all embodiments is that to achieve the accuracy required in the automotive industry it is necessary to compensate for manufacturing and assembly tolerances.
Since expensive devices are required to trim sensor systems for pressure and temperature, trimming is generally performed by the manufacturers of the pressure sensor themselves.
German Utility Model No. DE 297 14 223 U1 discloses a transmission control unit that has an electronic control circuit connected electrically to at least one pressure sensor for measuring the hydraulic pressure in the transmission. In this configuration, the electronic control circuit and the pressure sensor are provided in a common control housing. The control housing has a metallic base plate, which is connected pressure-tightly to a hydraulic unit of the transmission. An additional sensor housing is provided for the pressure sensor.
It is accordingly an object of the invention to provide a control unit which overcomes the above-mentioned disadvantages of the heretofore-known control units of this general type and into which systems that detect pressure can be integrated mechanically and electrically in an economical and reliable manner, taking into account the above-mentioned requirements.
With the foregoing and other objects in view there is provided, in accordance with the invention, in combination with a transmission, in particular an automatic transmission, having a hydraulic unit, a control unit, including:
an electronic control circuit;
at least one pressure sensor electrically connected to the electronic control circuit for measuring a hydraulic pressure in the transmission, the pressure sensor being configured as a silicon chip;
a common housing having a metallic base plate connected pressure-tightly to the hydraulic unit of the transmission;
the pressure sensor and the electronic control circuit being accommodated in the common housing;
a metallic support plate for the pressure sensor, the metallic support plate being fitted into the metallic base plate;
the metallic support plate having an end face disposed in the common housing, and the metallic support plate being formed with a borehole, the pressure sensor being subjected, via the borehole, to a pressure prevailing in the hydraulic unit; and
a metallic ring mounted on the end face of the metallic support plate, and the pressure sensor being mounted on the metallic ring.
In other words, the control unit according to the invention has an electronic control circuit, which is connected electrically to at least one pressure sensor for measuring the hydraulic pressure in the transmission. The pressure sensor and the electronic control circuit are accommodated in a common housing that has a metallic base plate, which is connected pressure-tightly to a hydraulic unit of the transmission and into which a metallic support ate for the pressure sensor is fitted. The support plate for the pressure sensor is provided with a hole through which the pressure sensor is subjected to the pressure prevailing in the hydraulic unit. A metallic ring is secured on the end face of the support plate, the end face being disposed in the housing, and a sensor element configured as a silicon chip is mounted on the metallic ring. A glass cylinder can be inserted between the metallic ring and the pressure sensor.
With the objects of the invention in view there is also provided, in combination with an air induction pipe, a control unit, including:
an electronic control circuit;
a pressure sensor electrically connected to the electronic control circuit for measuring an air pressure in the air induction pipe, in particular the vacuum in the air induction pipe, the pressure sensor being configured as a silicon chip;
a common housing having a metallic base plate connected pressure-tightly to the air induction pipe;
the pressure sensor and the electronic control circuit being accommodated in the common housing;
a metallic support plate for the pressure sensor, the metallic support plate being fitted into the metallic base plate;
the metallic support plate having an end face disposed in the common housing, and the metallic support plate being formed with a borehole, the pressure sensor being subjected, via the borehole, to a pressure, in particular the vacuum, prevailing in the air induction pipe; and
a metallic ring mounted on the end face of the metallic support plate, and the pressure sensor being mounted on the metallic ring.
The advantages of the invention are in particular the simple and economical integration of a pressure sensor into the pressure-tight and fluid-tight housing of an electronic control circuit. An additional expensive housing for the pressure sensor is no longer necessary, and the electrical contact feed-throughs through the housing are also eliminated. The sensor can be connected to the control circuit economically simply by bonding. The housing can be sealed off from the hydraulic unit through the use of a simple axial O-ring.
According to another feature of the invention, the metal ring has a surface; and a gold coating is provided on the surface.
According to yet another feature of the invention, an O-ring is provided for sealing the metallic support plate from the hydraulic unit.
According to a further feature of the invention, a substrate with electrical trimming elements or adjusting elements is provided, the substrate being provided on the metallic support plate.
According to another feature of the invention, the metallic support plate is composed of a relatively harder metallic material; and the metallic base plate is composed of a relatively softer material.
According to yet another feature of the invention, the metallic support plate is composed of steel; and the metallic base plate is composed of aluminum.
According to yet a further feature of the invention, a glass cylinder is inserted between the metallic ring and the pressure sensor.
According to anoth feature of the invention e transmission is an automatic transmission.
According to another feature of the invention, the control unit is provided for a transmission of a motor vehicle.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a control unit in a motor vehicle, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.